Nowadays, an embedded light device is assembled via a spring or an elastic piece. However, the embedded light device cannot suit ceilings with different thicknesses. Further, the stability of the assembled light device is relatively weak. When the spring or the elastic piece has been used for a long time or is fatigued, the fixedly assembly is disengaged. In addition, it is very difficult to detach this kind of embedded light device, and a user may be injured by the released elastic piece. Accordingly, in the related art, embedded light devices are relatively weak in stability, reliability and safety, and it is difficult to maintain and detach the light devices.